1. Field of the Invention
The invention relates to a method for transmission power control, and more particularly to a method for multi-level transmission power control of a communications apparatus.
2. Description of the Related Art
Bluetooth is a low-power, short-range wireless networking standard designed for local area voice and data transfer. Bluetooth radios operate in the unlicensed ISM band at 2.4 GHz with a set of 79 hop carriers with 1 MHz spacing. A master-slave communication model with a frequency hopping spread spectrum (FHSS) transmission technique is adopted in the Bluetooth specification to ensure protection from interference and security of data. A collection of Bluetooth devices may be connected in an Ad Hoc fashion. The Bluetooth devices may connect to each other to form a network known as a piconet. One Bluetooth device may act as a master device for the piconet, while the other devices may concurrently operate as slave devices. At the maximum, 8 active Bluetooth devices may participate in the one piconet. Time may be divided into slots of 625 μs in the piconet. The master and slaves may alternate transmission opportunities in a time-division duplex (TDD) fashion. The master controls the formation of the Bluetooth communication links and communication procedures with the slaves within the piconet. A slave may be enabled for transmission, only after being polled by the master.
Bluetooth low energy (BLE) is a low power Bluetooth protocol for small, battery-powered devices, such as watches, wireless keyboards, gaming and sports sensors, or other manner. Devices using Bluetooth low energy wireless technology are expected to consume a fraction of the power of classic Bluetooth enabled products.
In order to further save transmission power, a method for multi-level transmission power control, which is applicable to both the Bluetooth and Bluetooth low energy technology and even other wireless communication technologies such as IEEE 802.11 is required.